Arrangement for indicating leakage of seal for valve stem of fire hydrant



EL 3,054,617 NG LEAKAGE OF SEAL FOR OF FIRE Oct. 9,

Sept. 18, 1962 F. H. MU LER ARRANGEMENT FOR I CATI VALVE s HYDRANT Filed 1959 IN VENTOR FRANK H. MUELLER ATTORNEYS.

United States This invention relates to a top closure plate for a fire hydrant, and more particularly to a top plate closure having means to readily indicate a leak of the seal interposed between the top plate closure and the upper portion of the valve operating stem.

The top plate closure of the present invention may be employed with any known fire hydrant construction, but is preferably employed with the hydrant disclosed in the application of James H. Skomp Serial No. 854,416, filed November 20, 1959. The present invention is an improvement of the top plate closure disclosed in the above mentioned application.

It is known to provide a seal between the upper operating portion of a valve stem used in fire hydrants and the top plate closure which also holds the standard operating nut or screw and weather cap. Attempts have been made to provide a sealed lubricant-containing chamber in the top plate which, in some construction, encompasses the mechanism for causing rectilinear motion of the valve stem within the hydrant barrel to open or close the hydrant valve at the lower end of the barrel. After a long period of time the sealing means between the valve stem and the top plate deteriorates or otherwise becomes ineffective and allows water under main pressure to escape past the seal when the hydrant valve is open. Should a lubricant be employed within the sealed chamber, the lubricant sometimes is carried out of the chamber by the water under pressure and flows out upon the outer surface of the hydrant. The lubricant forced out of the hydrant, if not immediately wiped off, may stain the top of the hydrant or cause it to collect dirt, either occurrence rendering the hydrant unsightly.

The present invention provides a sealed lubricant chamber for the valve stem operating mechanism within the top closure plate wherein the aforementioned shortcoming is eliminated, in that should the sealing means deteriorate to a point of allowing leakage, the lubricant contained within the chamber will not be forced outwardly onto the hydrant but will remain within the chamber, allowing only the water under pressure to escape to indicate the sealing failure. The sealing means is so disposed within the topplate closure that once the leak has been detected, it may readily be remedied by replacing one sealing gasket disposed within a portion of the top plate.

It is an object, therefore, of this invention to provide an improved top closure plate for a fire hydrant having a lubricating chamber disposed therein to lubricate the valve stem operating mechanism.

It is another object of the present invention to provide an improved top closure plate for fire hydrants having a sealed lubrication chamber disposed therein to lubricate the valve stem operating mechanism, and incorporating means to readily detect any failure of the seal between the stem and the plate when the hydrant valve is open.

These and further objects and advantages will be readily apparent to those skilled in the art upon reading the following detailed description taken in conjunction with the appended drawings in which:

FIGURE 1 is a fragmentary plan view of a hydrant top plate embodying this invention; and

FIGURE 2 is a vertical sectional view of the hydrant atent O Uce top plate shown in FIG. 1 and showing such plate operatively secured to a fire hydrant barrel.

The preferred embodiment of the hydrant top plate comprises a substantially flat circular plate portion 10 which is centrally apertured, as at 12, for the rotative reception of a valve stem drive or operating screw 14. Depending from the underside of the annular plate.por-' tion It is a skirt or sleeve 16' concentric with and of larger interior diameter than the'aperture 12. The sleeve 16 has a pair of longitudinally spaced interior circumferential grooves 18 at its lower end adapted to receive sealing O- ings 20 and 22. The wall of the aperture 12 is provided with an internal circumferential groove 24 adapted to receive a sealing O-ring 26. All of the aforementioned O-rings are coaxially aligned to provide fluid seals for the uppermost portion of a hydrant valve stem when the top plate is assembled to the top of a hydrant barrel, as later described.

The annular plate portion 10 has a plurality of circumferentially spaced apertures 28 adjacent its outer edge, which apertures are in alignment with tapped openings 30 in the upper end of a hydrant barrel 32. Preferably, a plurality of integral radially extending reinforcing ribs 34 are formed on the undersurface of annular top plate portion 10. Referring to FIG. 2, the top plate 10 is secured to the upper end of the hydrant barrel 32 by screws 38 extending through the apertures 28 in the plate and into the tapped openings 30. The usual sealing gasket 40 is interposed between the hydrant barrel 32 and the top plate 10. With the top plate 10 thus assembled to the hydrant barrel 32, the drive or operating screw 14 is rotatively received within central aperture 12 and is suitably connected to the usual noncircular operating head 44 by pin 46 which also secures a weather cap 48 to the head. A seal is provided between the annular plate portion 10 and the operating screw 14 by the O-ring 26 disposed in the internal circumferential groove 24 in the aperture 12. The operating screw 14 is provided with a circumferential flange 50 which bears against the underside of annular plate portion 10, while an annular surface 52 of operating head 44 bears against the upper side of annular plate portion 10 to retain the operating screw 14 against axial movement, while permitting the same to be freely rotatable by an appropriate wrench engaged with the operating head 44.

Secured on the upper end of the hydrant valve stem (not shown) by any suitable connection, such as a pin and socket (also not shown) is a feed nut 54 threadedly' engaged with the operating screw 14 so that rotation of the latter will effect reciprocation of the valve stem to open and close the usual hydrant valve (not shown) secured thereto.

The depending sleeve 16 surrounds the feed nut 54 and operating screw 14 so that the longitudinally spaced O-rings 20 and 22 disposed at the sleeves lower end engage the outer cylindrical surface portion 56 of the feed nut 54. The upper O-ring 20 constitutes a fluid seal, while the lower O-ring 22 constitutes a wiper for the feed nut 54 and protects the sealing O-ring 2t] from being damaged by any dirt or corrosion which may be on the cylindrical surface portion 56 of the feed nut.

The sleeve 16 has a passage 60 extending from the top of annular plate portion 10 into communication with the interior of the sleeve at a position in its lower portion slightly above the upper sealing O-ring 20. A pressure relief valve 62 is disposed within the passage 60 at the upper surface of annular plate portion 10. An additional passage 64 extends through the annular plate portion 10' into the upper end of the interior of the sleeve 16 to allow for the injection of lubricating oil into the interior of the sleeve 16 to lubricate operating screw 14 and the cooperating feed nut 54. The outer end of the passage 64 is closed by a lubricant injection fitting (not shown) or by a plug 66, as shown in FIG. 2 of the drawings.

With the. aforementioned parts thus assembled in a hydrant, O-ring 20 provides a fluid seal to prevent water under main pressure from escaping from the top of the hydrant other than through the usual hose nozzles (not shown) when the hydrant valve is opened. Should O-ring 20 become deformed or weakened or otherwise lose its sealing capacity after prolonged usage, when the hydrant valve is opened, water under main pressure will pass between the O-ring 20 and the cylindrical surface 56 of feed nut 54. By' having passage 60 communicating with the interior of sleeve 16 at its lower end slightly above .O-ring 20, water passing the O-ring will enter the passage 60 and move upwardly therethrough into pressure relief valve 62 and then outwardly on the upper surface of annular plate portion indicating the failure of the seal.

The lubricating oil which has been injected into the interior of sleeve 16, being lighter than the water, will readily float on top of any water in the chamber within the sleeve 16, and so will be pushed into the upper portion of such chamber while the water escapes through the passage 60. Should passage 60 communicate with the upper portion of the chamber within the sleeve 16, rather than the lower portion, as set forth above, the lubricating oil would naturally be forced through the passage and out through pressure relief valve 62. This latter course of the lubricating oil is undesirable in that the lubricating oil would adhere to the upper surface of the annular plate portion 10 or run down the side of hydrant barrel 32, and if not cleaned off would readily collect dirt, thus providing an unsightly hydrant. By having passage 60 communicate with the lower interior portion of sleeve 16, the above mentioned undesirable effect is eliminated, as the oil is trapped within the upper interior'portion of the sleeve, while only the Water passes through passage 60 and outwardly onto the exterior of the hydrant.

The operator of the hydrant will be readily able to detect the failure of O-ring 20 to provide an adequate fluid seal by observing the how of water from pressure relief valve 62. Of course, such flow can take place even though all the lubricant may have leaked down into the hydrant barrel. Upon notification of the leakage, it is but a relatively simple matter to remove the hydrant topplate and replace the inoperative O-ring 20 with a new one.

It will thus be seen that there has been provided by this invention a device in which the various objects hereinbefore set forth, together with many practical advantages, are successfully achieved. As various possible embodiments may be made of the mechanical features of the above invention, all without departing from the scope thereof, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1'. A top closure for a fire hydrant barrel comprising a plate portion adapted to be removably mounted to the top of a hydrant barrel; means disposed on said plate for rotatively receiving a portion of a hydrant valve stem operating mechanism; said means, together with the mechanism, defining a closed lubricant chamber enclosing the mechanism portion; a seal between said mechanism portion and. a lower portion of said chamber; and means including a pressure relief valve communicating a lower portion of said lubricant chamber with the atmosphere.

2. A top closure for a fire hydrant barrel comprisng: a plate portion adapted to bev removably mounted to the top of the hydrant barrel and having an aperture to rotatively receive a portion of hydrant valve stem operat ing mechanism; a sleeve depending from the underside of said plate portion concentric with said aperture for surrounding the mechanism; sealing means disposed in said aperture and in a lower portion of said sleeve for separate engagement with the operating mechanism; means including a pressure relief valve communicating the interior of said sleeve at its lower portion and above said lower portion sealing means with the atmosphere; and means to inject a lubricant into the interior of said sleeve between said sealing means.

3. In a fire hydrant having a barrel, a vertically reciprocable valve stem, and operating mechanism for said stem within the upper portion of said barrel, the combination comprising: a closed chamber enclosing said stem operating mechanism with the latter projecting below said chamber Within said barrel and above said chamber out of the top of said hydrant for operative accessibility; seals between said mechanism and the upper and lower walls of said chamber; means for charging said chamber with lubricant; a passageway leading from a lower portion of said chamber to the exterior of the hydrant barrel; and a pressure relief valve interposed in said passageway.

4. The structure defined in claim 3 wherein the chamher is defined in part by a top closure plate detachably secured to the top of the hydrant barrel and by a sleeve depending from the underside of said plate, and wherein the passageway extends through a wall of said sleeve adjacent the lower end of the latter but above the seal thereat.

References Cited in the file of this patent UNITED STATES PATENTS 2,038,889 Clade Apr. 28, 1936 2,100,862 Lofton Nov. 30, 1937 2,211,122 Howard Aug. 13, 1940 2,314,683 Berry Mar. 23, 1943 2,493,152 Malcolm Jan. 3, 1950 2,576,631 Mueller Nov. 27, 1951 2,633,143 Simon Mar. 31, 1953 

